Generating control data for a printing system

ABSTRACT

A method of generating control data for a printing system includes receiving image data comprising an image to be printed by the printing system, determining a presence of a control mark in the image data, and generating control data for the printing system based on the control mark, the control data including at least an indication of the presence of the control mark.

PRIORITY INFORMATION

This application is a continuation of U.S. National Stage Application No16/756,278 filed on Apr. 15, 2020, which claims priority toInternational Application No. PCT/US2017/067340 filed on Dec. 19, 2017.The contents of which are incorporated herein by reference in itsentirety.

BACKGROUND

Printing devices are arranged to printing fluid, such as ink, on tosubstrates. A component of a printing system, such as a Digital FrontEnd (DFE), receives an image to be printed and can instruct a printingapparatus to print control marks at specific locations on the substrate.Once the image and control marks have been printed, the control markscan be read by a human and/or an imaging device. Example control marksmay include registration marks, used to help ensure that the print isaligned properly.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of the present disclosure will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate features of the presentdisclosure, and wherein:

FIG. 1 is a diagrammatic representation of a printing system inaccordance with an example;

FIG. 2 is a diagrammatic representation of a printing system inaccordance with an example;

FIG. 3 is a diagrammatic representation of image data in accordance withan example;

FIG. 4 is a diagrammatic representation of a plan view of a portion ofthe printing system in accordance with an example;

FIG. 5 is a diagrammatic representation of image data in accordance withan example;

FIG. 6 is a diagrammatic representation of imposition applied to theimage data of FIG. 5 in accordance with an example;

FIG. 7 is a flow diagram showing a method of generating control data fora printing system in accordance with an example; and

FIG. 8 is a diagrammatic representation of an example set ofcomputer-readable instructions within a non-transitory computer-readablestorage medium.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details of certain examples are set forth. Reference in thespecification to “an example” or similar language means that aparticular feature, structure, or characteristic described in connectionwith the example is included in at least that one example, but notnecessarily in other examples.

As described herein, an example printing system comprises a digitalfront end comprising a processor and memory. The printing system furthercomprises a printing apparatus communicatively coupled to the digitalfront end. The digital front end is configured to receive image datacomprising an image to be printed by the printing apparatus, and todetermine a presence of a control mark in the image data. The digitalfront end is further configured to generate control data based on thecontrol mark, where the control data includes an indication of thepresence of the control mark. The digital front end is furtherconfigured to transmit the control data to the printing apparatus.

An example digital front end (DFE) may be embodied as a computer system,and a user wishing to print one or more images as part of a print job,may upload, transfer, or make available one or more digital files, sothat they are accessible by the DFE. In broad terms, the DFE preparesthe digital files for printing, and formats the files so that a printercan print the images.

In an example workflow process, a user may create a document forprinting using specific design software. The digital file created may beformatted in a page description language, which describes the appearanceof the printed page. Example page description languages includePersonalized Print Markup Language (PPML), Job Layout (JLYT), PrinterCommand Language (PCL) and PostScript, among others. Alternatively, thedigital file may comprise an image file such as a Tagged Image FileFormat (TIFF) file or a Joint Photographic Experts Group (JPEG) file.The user may then upload or transfer the file to a printing system sothat it can be processed by a DFE. Before printing, the digital file mayneed to be converted to a format that can be interpreted by a printingapparatus. As such, one function of the DFE may be to rasterize the fileto convert the file to raster data, such as a bitmap. Hence, in someexamples the DFE incorporates Raster Image Processing techniques if thedigital file is in a format that cannot be interpreted by the printingapparatus. The converted file can then be transmitted to the printingapparatus so that the image can be printed.

In comparative systems, the DFE may also add one or more control marksto the digital file before or after the file has been converted to abitmap. A printing technician may control whether these are applied bythe DFE or not. These control marks are then printed onto the substratealong with an image. For example, these control marks are usuallyprinted in peripheral regions of the substrate in a region outside ofthe printed image.

These control marks can help a human operator determine whether theimage printed onto the substrate is an accurate representation of theimage that was intended to be printed. For example, an example controlmark may include a registration mark, used to ensure that each colourseparation, such as Cyan, Magenta, Yellow and Black separations, areprinted in alignment. If the printed registration mark does not appearas expected once printed, the operator may need to calibrate the printerapparatus before re-printing the image. For example, they may need toalter the alignment settings. Another example control mark may includecrop marks. These include lines printed onto the substrate to indicatewhere the substrate should be trimmed and cut.

In certain comparative systems, the registration calibration procedureand/or the trimming can be an automated process. For example, imagingequipment, such as cameras or scanners can image the printed substrateto detect the control marks. Once detected, the printing apparatus maythen automatically trim the substrate at the locations indicated, and/orapply a registration calibration procedure, if one is suitable, based onthe appearance of the registration mark.

In these comparative systems, the DFE is aware of the presence and/orlocation of the control marks as a result of these being added by, orwithin, the DFE. However, some users prefer to add these control marksthemselves before submitting a print job to the DFE. For example, thecontrol marks may already be embedded in the images present in a pagedescription language file received by the DFE. The DFE is thereforeunaware of the presence of these control marks because, to the DFE, theyare indistinguishable from the image to be printed.

Certain examples described herein provide a system whereby a DFE candetect or determine a presence of control marks in a digital filecreated by a user. Hence, control marks added by a user anywhere withinthe digital file can be detected. After detection, the DFE generatescontrol data based on the control mark and transmits this control datato the printing apparatus. Accordingly, the DFE and printing apparatusare aware of the presence of these control marks, regardless of whetherthey were added by a user as part of the design process, or by the DFE.

FIG. 1 is a diagrammatic representation of a printing system 100 inaccordance with an example. In the printing system 100, print job datais received by a digital front end 104. The digital front end (DFE) 104may be a computer system comprising one or more processors and memory,e.g. may be implemented via at least one processor executing computerprogram code retrieved from the memory. Regardless of form, the DFE mayimplement an application programming interface (API) configured toreceive the print job data.

Print job data includes image data 102 which comprises, or is associatedwith an image to be printed by a printing apparatus 106. The image datamay represent an image, or images, comprising a plurality of pixelvalues. The image data may be in any format, such as Portable DocumentFormat (PDF), JLYT, or JPEG, for example. The image may form theentirety of the image data (e.g. in the case of a TIFF or JPEG file) orthe image data may be extracted from a given file format. The print jobdata may also comprise additional data associated with the print job,such as settings, preferences or options. The image data 102 and/orprint job data may be received from computing components communicativelycoupled to the DFE 104, e.g. from a client device, an email server, or anetwork storage device. Upon receipt, the DFE 104 processes the imagedata 102 and print job data in order to print an image contained withinthe image data 102 using the printing apparatus 106. Processing the datacomprises, amongst other things, determining a presence of a controlmark in the image data and generating control data based on the controlmark, where the control data includes an indication of the presence ofthe control mark. This control data can be transmitted to the printingapparatus 106. The printing apparatus 106 may comprise one or morepre-print or post-print components and a printer, for example.

FIG. 2 is a diagrammatic representation of a printing system 200 inaccordance with an example. In the printing system 200, print job data,and therefore image data, is received by the digital front end 204. Inthis example, the printing apparatus comprises a printer 206 to printthe image, as well as additional pre-print components arranged beforethe printer, and additional post-print components arranged after theprinter. The printer 206 is communicatively coupled to the DFE 204 viaone or more wired or wireless communication paths, depicted as dashedlines in the Figure. In this way, data is transmitted between the DFE204 and the printer 206. The printer 206 may be a digital printer or anoffset printer, for example, and is configured to apply printing fluid,such as printing ink, to a substrate 208. In FIG. 2, the substrate 208is depicted as a web substrate, such as a continuous roll of paper,which is later cut into individual portions. The substrate travels in aprint direction, indicated by arrow 212. In other examples, thesubstrate may already be cut into individual portions before beingprinted upon.

The image data 102 and/or print job data may be received from anycomputing components communicatively coupled to the DFE 204. The datamay be received from one or more computer terminals 205 that arecommunicatively coupled to the DFE 204. For example, the computerterminals may be connected to the DFE 204 via a computer network, suchas the Internet, or they may be collocated with the DFE 204.Additionally, or alternatively, the image data 102 and/or print job datamay be received from a storage medium 210. The storage medium 210 may becollocated with the DFE 204, or may be connected via the Internet forexample. In one example, the storage medium 210 is a cloud server.

Upon receipt of the image data and/or print job data, the DFE 204processes the image data and/or print job data in order to print animage using the printer apparatus 206. For example, one function of theDFE may be to rasterize the image data to convert the image data into abitmap format. Hence, in some examples the DFE incorporates Raster ImageProcessing techniques if the digital file is in a format that cannot beinterpreted by the printer.

As mentioned, in some instances, the image data may comprise one or morecontrol marks. For example, the image data may include an image to beprinted and one or more images of control marks that were added prior tothe image data being received by the DFE 204. To prepare the printer 206and any other pre-print, or post-print components of the system 200, theDFE is configured to implement a method whereby one or more controlmarks are detected within the image data. For example, the computerimplemented method may comprise the DFE 204 determining a presence ofthe control mark in the image data. This may include parsing, orscanning the image data, or a portion of the image data, to locate acontrol mark in the image data.

In one example, the DFE 204 parses the image data to determine thepresence of a control mark by using a reference database which comprisesone or more standard control marks. The DFE may therefore compare eachentry in the reference database against the image data to determinewhether the image data comprises any of the standard control marks. Eachstandard control mark may be associated with a specific arrangement ofpixels, for example, and the DFE 204 is configured to search and locatethe specific arrangement of pixels. In some examples, standard controlmarks are located and placed within certain regions of an image, hencethe DFE may not parse the whole image but certain regions to increasethe efficiency in which the control marks are detected.

In some examples, the reference database associates each control markwith a specific function. For example, a registration mark may beassociated with a specific set of instructions that are to beimplemented by one or more components of the printing system 200 toachieve registration. A cutting mark may also be associated with aspecific set of instructions that are to be implemented by one or morecomponents of the printing system 200 to achieve cutting of thesubstrate at the correct location.

If the DFE 204 determines that a control mark is present within theimage data, the DFE is configured to generate control data for theprinting system 200 based on the control mark. The control data mayinclude an indication of the presence of the control mark. For example,the control data may specify that the image data is associated with aspecific control mark, e.g. a registration or cutting mark, and as such,the instructions associated with the control mark should be implementedwithin the printing system. In some examples the DFE also determines alocation of the control mark in the image data. For example, the DFE maystore a coordinate of the control mark. Hence, in some examples, thecontrol data further includes an indication of the location of thecontrol mark. The location may be defined with reference to the imagedata, or with reference to the location on the printed substrate. Insome examples, the control data includes information from the referencedatabase, such as details of, or pointers to a specific set ofinstructions that are to be implemented based on a control mark.However, in other examples the reference data is accessible by variouscomponents in the system 200, such that the control data need notcomprise information from the reference database.

Thus, by implementing the above method, the DFE 204 has determined thatthe image data comprises one or more control marks without the DFE beingused to specifically add these to the image data. In some examples theDFE 204 also adds control marks to the image data and includes anindication of these control marks in the control data, in addition tothose detected.

Once aware of the presence and/or location of the control marks, the DFEcan inform other components of the system 200 that these control marksare being used. To do this, the DFE transmits the control data, or arelevant subset of the control data to the various components of thesystem 200. In some examples, the control data also includes other printinformation used in the printing process, such as the printer settings,and the bitmap produced by the DFE 204 during rasterization. In otherexamples, the print information is transmitted separately. Componentsconfigured to receive the control data, such as the printer 206, maycomprise electronic circuitry, such as a processor or microprocessor andmemory that implements an application programming interface to receivethe control data. The control data can be used within the system toaugment the printing and calibration processes. Hence, by providingcontrol data, these processes can be correlated with the print job. Inone example, the control data comprises an indication of a “Front toBack” control mark that was detected within the image data by the DFE204. A front to back mark can indicate that dual sided printing is to beused. Hence, by providing the control data to the components of thesystem 200, a dual engine print press can accurately synchronizeprinting on both sides of the substrate.

As mentioned, printing fluid is applied to the substrate 208 by theprinter 206. To do so, the printer 206 receives the print informationand/or control data from the DFE 204. The ink applied by the printer 206will form the printed image, which includes the image to be printed aswell as one or more control marks. These control marks may have beenadded by the user and were thus present in the image data received bythe DFE, and/or may have been added by the DFE itself. The “image to beprinted” refers to the component of the image data that corresponds tothe image that the user desired to print, and does not include anystandard control marks. The “image data” received by the DFE thusincludes both data corresponding to the image to be printed, and datacorresponding to any control marks added by the user before submittingthe print job data to the DFE.

Once the printed image is formed on the surface of the substrate 208, animaging device, such as camera 214, may image certain regions of thesubstrate 208 to detect the presence and/or position of the controlmarks.

In some examples, the imaging device 214 receives the control data fromthe DFE, either directly or indirectly, via one or more communicationpaths. Hence, the imaging device 214 may be aware of the presence and/orlocation of one or more control marks within the image data. Using thiscontrol data, the imaging device may capture images of the printedsubstrate, and hence images of the control marks. For example, if thecontrol data indicates the location of one or more control marks, theimaging device may position itself relative to the substrate 208 toensure that its field of view encompasses the location of the controlmark being imaged.

If images of the control marks are captured by the imaging device 214,captured image data may be transmitted to other elements within theprinting system 200. For example, the imaging device 214 may transmitthis data to the DFE 204, to the printer 206, or to any other pre-printcomponents, such as the calibration assembly 218, or post-printcomponents, such as the cutting assembly 220 and the folding assembly222.

The calibration assembly 218 may be configured to perform any number ofcalibration procedures, including, but not limited to: registrationcalibration, scaling calibration, and colour calibration. Thecalibration assembly 218 may comprise one or more processors and memory.In some examples, the calibration assembly is a separate system, asdepicted in FIG. 2. However, in other examples the printer 206 maycomprise instructions and/or dedicated circuitry configured to performthe procedures used for calibration. In a further example, thecalibration procedures may be performed by the DFE 204.

In one example, the calibration assembly 218 receives data from theimaging device 214, such as one or more captured images of the printedsubstrate 208. For example, the captured image may include images of oneor more control marks printed onto the substrate 208. In addition, thecalibration assembly 218 may also receive the control data from the DFE204, and thereby use the control data to calibrate printing. Using thecaptured images and the control data, the calibration assembly 218 canimplement instructions associated with detected control marks.

Using the captured image data and control data, the calibration assembly218 may perform a registration calibration procedure. For example, thecaptured image may comprise a captured image of a registration controlmark. The control data may indicate that the registration control markis expected to be present in the captured image, and may also indicateinstructions of a procedure to be performed based on the control mark.For example, using the captured data, it can be determined whether anycolour separations printed by the printer 206 are misaligned. If it isdetermined that one or more separations are misaligned, the registrationcalibration procedure may determine a correction factor that should beapplied by the printer 206. For example, one or more updated alignmentsettings for the printer 206 may be determined. This data can betransmitted to the printer 206, so that any further images printed bythe printer 206 are modified to improve and/or correct alignment. Thisprocedure may be iterated one or more times until it is determined thatno further corrections are to be performed.

Similarly, using the captured image data and control data, thecalibration assembly 218 may perform a scaling calibration procedure.For example, the captured image may comprise a captured image of ascaling control mark, which may also be known as a Continuous ScalingControl (CSC) mark. The control data may indicate that the scalingcontrol mark is expected to be present in the captured image, and mayalso indicate instructions of a procedure to be performed based on thecontrol mark. For example, using the captured data it can be determinedwhether the image printed by the printer 206 is scaled correctly. If itis determined that the image is not scaled correctly, the scalingcalibration procedure may determine a correction factor that should beapplied by the printer 206. For example, one or more updated scalingsettings for the printer 206 may be determined. This data can betransmitted to the printer 206, so that any further images printed bythe printer 206 are more likely to comprise correctly scaled images.This procedure may be iterated one or more times until it is determinedthat no further corrections are to be performed.

Similarly, using the captured image data and control data, thecalibration assembly 218 may perform a colour calibration procedure. Forexample, the captured image may comprise a captured image of a referencecolour control mark, which may also be known as a Colour CalibrationControl (CCC) mark. The control data may indicate that the colourcontrol mark is expected to be present in the captured image, and mayalso indicate instructions of a procedure to be performed based on thecontrol mark. For example, using the captured data it can be determinedwhether the image printed by the printer 206 is coloured correctly. Ifit is determined that the image is not coloured correctly, the colourcalibration procedure may determine a correction factor that should beapplied by the printer 206. For example, one or more updated coloursettings for the printer 206 may be determined. This data can betransmitted to the printer 206, so that any further images printed bythe printer 206 are more likely to comprise correctly coloured images.This procedure may be iterated one or more times until it is determinedthat no further corrections are to be performed.

As mentioned, the imaging device 214 may also transmit data to thecutting assembly 220. The cutting assembly 220 may be configured toperform a cutting procedure, whereby the substrate 208 is cut, croppedor trimmed at the correct position according to cutting control marksprinted onto the substrate 208. For example, the cutting assembly 220receives data from the imaging device 214, such as one or more capturedimages of the printed substrate 208. The captured image may includeimages of one or more cutting control marks printed onto the substrate208.

The cutting assembly 220 may comprise one or more processors and memoryand components for cutting the substrate 208. In some examples, thecutting assembly does not receive data from the imaging device 214, andmay instead comprise its own imaging device 221. In some examples, datais received from both imaging devices 214, 221. Regardless of how thecutting assembly 220 receives the captured image data, the cuttingassembly 220 is configured to cut the substrate 208 into separate sheets224. In some examples, the cutting assembly 220 and/or imaging device221 also receives control data from the DFE 204. The imaging device 221may position itself based on the control data, for example in a positionable to detect the presence of the cutting control mark.

As mentioned, the imaging device 214 may also transmit data to thefolding assembly 222. The folding assembly 222 may be configured toperform a folding or scoring procedure, whereby the substrate 208 isfolded and/or scored at the correct position according to foldingcontrol marks printed onto the substrate 208. For example, the foldingassembly 222 receives data from the imaging device 214, such as one ormore captured images of the printed substrate 208. The captured imagemay include images of one or more folding control marks printed onto thesubstrate 208.

The folding assembly 222 may comprise one or more processors and memoryand components for folding and/or scoring the substrate 208. In someexamples, the folding assembly does not receive data from the imagingdevice 214, and may instead comprise its own imaging device 223. In someexamples, data is received from both imaging devices 214, 223.Regardless of how the folding assembly 222 receives the captured imagedata, the folding assembly 222 is configured to fold/cut the substrate208 as desired. In some examples, the folding assembly 222 and/orimaging device 223 also receives control data from the DFE 204. Theimaging device 223 may position itself based on the control data, forexample in a position able to detect the presence of the folding controlmark.

In the above described procedures, the generation of control data basedon detected control marks allows the system 200 to improve a workflow.By being provided with the control data, the efficiency of proceduresimplemented by the calibration assembly 218, the printer 206, thecutting assembly 220, the folding assembly 222, and one or more imagingdevices 214, 221, 223 can be improved.

To further improve the efficiency, the DFE 204 may determine thepresence of the control mark in the image data when instructed to do so.For example, a user may specify in the print job that their digital filecomprises control marks, and as such, the DFE may responsively parse theimage data for the presence of control marks. The user may indicate thiswithin instruction data for the print job, and the instruction data maytherefore comprise a flag indicating that the DFE is to automaticallydetermine the presence of a control mark in the image data. If the flagis not set, the DFE may not parse the image data, thus saving processingresources.

In some examples, the instruction data may also provide an indication ofwhich control mark(s) are included in the image data. Hence, the DFE 204may know which specific control marks to search for, which thereforefurther improves processing efficiency. For example, the DFE 204 maytherefore not compare every entry in the reference database against theimage data, but only those indicated by the user in the instructiondata.

FIG. 3 is a diagrammatic representation of image data 300 in accordancewith an example. The image data 300 comprises an image to be printed302, which is the region/area bounded by the imaginary dashed line. Theimage to be printed corresponds to the “useful” image that the usercreated. The image to be printed therefore does not comprise anystandard control marks. The region outside of the image to be printed,such as the area found in the margins 304 a, 304 b, may include one ormore standard control marks 306, such as the cutting control mark 306 a,and the registration control mark 306 b. During the design process, theuser has control over all of the image data 300. For example, the areawithin the margins 304 a, 304 b are accessible to the user, such thatthe user can place or draw the control marks 306 b in the margins 304 a,304 b.

It can be seen that due to the presence of these standard control marks306 within the margin, blank space on the substrate will be wasted oncethe image to be printed and the standard control marks have been printedonto the substrate. To lessen this effect, some features of the image tobe printed 302 can comprise “hidden” non-standard control marks, suchthat a control mark is a component of the image to be printed, ratherthan being located in a region outside of the image to be printed.

In one example, the image to be printed 302 comprises one or morefeatures 308 a, 308 b, 308 c. Each referenced feature may comprise acertain colour or shape, for example. In one example, the featurescorrespond to different objects within the image 302. The user mayspecify within the print job that a feature within the image to beprinted is to be used as a control mark. This means that the equivalent“standard” control mark does not need to be printed, which can help savespace on the substrate. A standard control mark here refers to controlmarks that are usually used and associated with the particular controlmark function.

In one example, the two features 308 c may be designated as scalingcontrol marks. This designation may be an automated procedure, or a usermay manually specify these features are to be used. During the scalingcalibration procedure, scaling may be set/fixed based on the verticalscaling of these control marks, for example. Accordingly, space on thesubstrate can be saved.

In some examples therefore, the DFE may also receive an indication thatthe image data comprises “non-standard” control marks that arecomponents of the image to be printed. The DFE may also receive anindication of the appearance of the control mark, such that its presenceand/or location can be determined by the DFE when the image data isparsed by the DFE. This procedure can be performed alternative to, or inaddition to the DFE parsing portion 302 within the image data todetermine whether portion 302 comprises any standard control marks. Insome examples the DFE also adds an entry to the control mark referencedatabase corresponding to the non-standard control mark.

FIG. 4 is a diagrammatic representation of a plan view of a portion of aprinting system in accordance with an example. The portion of theprinting system may be a portion of printing systems 100 or 200, forexample.

The printing system comprises an imaging device 402 moveable along arail 404. As such, the imaging device 402 can image regions of thesubstrate 406 which moves beneath the imaging device, in a transportdirection indicated by arrow 408. The substrate 406 has printed thereon,a printed image, which includes an image region corresponding to theimage to be printed 410 and one or more control marks 412. As explainedin relation to FIG. 3, the region corresponding to the image to beprinted 410 may also comprise one or more non-standard control marks414.

To detect these control marks 412, 414, the imaging device can moveacross the substrate in a direction perpendicular to the transportdirection 408. In other examples however, the imagining device can alsomove parallel to the transport direction, and/or in the verticaldirection, such as in a direction into and out of the page. In FIG. 4,the imaging device is located at a first position, as shown by the solidline. The imaging device 402 may move to a second position, indicated bythe dashed line.

In some examples, the positioning of the imaging device 402 is changedbased on the control data generated by the DFE. For example, the controldata may include an indication of the location of a control mark. Assuch, upon receipt of the control data, the imaging device 402 mayadjust its position so that it is able to capture an image of thecontrol mark located on the substrate 406. Hence, the control dataallows the imaging device to more effectively detect the presence of thecontrol marks on the substrate.

FIG. 5 is a diagrammatic representation of image data 500 in accordancewith an example. The image data 500 comprises an image to be printed 502and one or more standard control marks, such as the registration controlmark 504, and the colour control mark 506.

As depicted, the image data 500 received by the DFE includes one imageto be printed 502. The image, once printed onto a substrate will occupya certain area on the substrate. To maximize space on the substrate,imposition may be applied. Imposition refers to the process whereby theimage to be printed is replicated and arranged so that when printed ontoa substrate, space is maximized. This ensures that blank space isminimized, which may save costs and materials associated with the printjob.

FIG. 6 is a diagrammatic representation of a substrate for whichimposition has been applied to the image data of FIG. 5. In thisexample, the image to be printed 502 has been replicated and arrangedbefore being printed on to the substrate 600. In this example, thismeans that two sets of the image to be printed 502 fit along the widthof the substrate 600. However, rather than also replicating all of thecontrol marks 504, 506 present in the image data 500, a subset may bereplicated and printed. For instance, control mark 504 has beenreplicated for every image to be printed 502, whereas control mark 506has not, to ensure that two sets of the image to be printed fit alongthe substrate. Thus, in some examples a subset of the plurality ofcontrol marks are printed, which can further help maximize space on thesubstrate. Hence, it may be determined that not all of the control marksneed to be replicated. In some examples, this determination may be madebased on the type of control mark.

Accordingly, the DFE may be configured to generate updated image data,referred to as “print data”, comprising two or more sets of the image tobe printed. While the image data originally comprised a plurality ofcontrol marks, the print data may comprise a subset of the plurality ofcontrol marks. The print data may also comprise data corresponding to asubset of the plurality of control marks. Hence, control data generatedby the DFE includes an indication and/or location of the presence of asubset of the plurality of control marks.

In one example, the DFE detects control marks 504 and 506, as well asthe image to be printed 502. To create the print data, the DFE mayimport the image to be printed 502 into an imposition template, and thedetected control marks 504, 506 can be imported into the impositiontemplate in different locations and/or in different quantities. Forexample, not all of the detected control marks are replicated the samenumber of times as the image to be printed 502. An imposition templatemay be similar to that shown in FIG. 6, but with blank regions in thelocations 502.

In one example, not all detected control marks are replicated within theprint data. For example, in some examples, control marks are removedentirely from the print data.

FIG. 7 is a flow diagram showing a method 700 according to an example.The method can be performed by the example digital front end 104, 204discussed in relation to FIGS. 1 and 2, and is a method of generatingcontrol data for a printing system 100, 200. The method may be computerimplemented.

At block 702, the method comprises receiving image data comprising animage to be printed by the printing system. At block 704, the methodcomprises determining a presence of a control mark in the image data. Atblock 706, the method comprises generating control data for the printingsystem based on the control mark, the control data including at least anindication of the presence of the control mark.

In some examples, the method may further comprise determining a locationof the control mark in the image data, wherein the control data furtherincludes an indication of the location of the control mark.

In some example methods, the control mark is a component of the image tobe printed. In some example methods, the control mark is located in aregion outside of the image to be printed within the image data.

In some examples, the method may further comprise receiving instructiondata for a print job associated with the image data at a digital frontend of the printing system, and determining whether the instruction datacomprises a flag, the flag indicating that the digital front end is toautomatically determine the presence of the control mark in the imagedata. Hence, determining the presence of the control mark in the imagedata is performed by the digital front end responsive to the instructiondata comprising the flag.

In some examples, the method may further comprise generating print datacomprising two or more sets of the image to be printed, the image datacomprising a plurality of control marks. Accordingly, generating controldata for the printing system comprises generating control data includingan indication of the presence of a subset of the plurality of controlmarks. Such a method is described in relation to FIGS. 5 and 6.

In some example methods, parsing the image data comprises parsing aportion of the image data to locate a control mark in the image data.

Certain system components and methods described herein may beimplemented by way of non-transitory computer program code that isstorable on a non-transitory storage medium. In some examples, thedigital front end may comprise a non-transitory computer readablestorage medium comprising a set of computer-readable instructions storedthereon. The DFE may further comprise one or more processors.

FIG. 8 shows an example of such a non-transitory computer-readablestorage medium 800 comprising a set of computer readable instructions801 which, when executed by at least one processor 803, cause theprocessor(s) 803 to perform a method according to examples describedherein. The computer readable instructions 800 may be retrieved from amachine-readable media, e.g. any media that can contain, store, ormaintain programs and data for use by or in connection with aninstruction execution system. In this case, machine-readable media cancomprise any one of many physical media such as, for example,electronic, magnetic, optical, electromagnetic, or semiconductor media.More specific examples of suitable machine-readable media include, butare not limited to, a hard drive, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory, or aportable disc.

In an example, instructions 801 cause the processor 803 to, at block802, obtain image data corresponding to an image to be printed by aprinting system. At block 804, the instructions 801 cause the processor803 to parse the image data to locate a control mark in the image data.At block 806, the instructions 801 cause the processor 803 to generatecontrol data based on the control mark, the control data including anindication of the presence of the control mark. At block 808, theinstructions 801 cause the processor 803 to transmit the control data tothe printing system.

In some examples, the instructions 801 may further cause the processor803 to determine a location of the control mark in the image data andgenerate the control data to include an indication of the location ofthe control mark.

In some examples, parsing the image data comprises parsing a portion ofthe image data to locate a control mark in the image data.

In some examples, the instructions 801 may further cause the processor803 to obtain instruction data for a print job associated with the imagedata and determine whether the instruction data comprises a flag, theflag indicating that the processor is to automatically parse the imagedata to locate a control mark in the image data. Accordingly, parsingthe image data to locate the control mark in the image data is performedby the processor responsive to the instruction data comprising the flag.

The described printing system therefore improves the printing processwhen a user includes control marks in the image data.

The preceding description has been presented to illustrate and describeexamples of the principles described. This description is not intendedto be exhaustive or to limit these principles to any precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching. It is to be understood that any feature described inrelation to any one example may be used alone, or in combination withother features described, and may also be used in combination with anyfeatures of any other of the examples, or any combination of any otherof the examples.

What is claimed is:
 1. A printing device, comprising: a processor; and anon transitory memory resource storing machine-readable instructionsstored thereon that, when executed, cause the processor to: detect acontrol mark within image data associated with a print job; generatecontrol data for the print job based on the control mark, wherein thecontrol data includes a location of the control mark within an image tobe printed; apply printing fluid to a substrate to generate the imagebased on the control data; and determine a correction factor for theprinting device based on a captured image of the control mark.
 2. Theprinting device of claim 1, wherein the correction factor includes analignment setting adjustment of the printing device.
 3. The printingdevice of claim 1, wherein the correction factor includes a scalingcalibration procedure for the printing device.
 4. The printing device ofclaim 1, wherein the correction factor includes a color calibrationprocedure for the printing device.
 5. The printing device of claim 1,wherein the control mark is detected within the image data in responseto an instruction that the control mark is within the image data.
 6. Theprinting device of claim 1, wherein the control mark is a component ofthe image printed on the substrate.
 7. The printing device of claim 6,wherein the control mark is a hidden non-standard control mark.
 8. Anon-transitory memory resource storing machine-readable instructionsstored thereon that, when executed, cause a processor of a computingdevice to: select a feature from a plurality of features within an imageto be printed to be utilized as a control mark for a print job; generatecontrol data for the print job based on the selected control mark,wherein the control data includes a location of the control mark withinthe image to be printed; and determine a correction factor for aprinting device based on a captured image of the control mark.
 9. Thememory resource of claim 8, wherein the processor is to instruct animaging device to be positioned at a particular location based on thelocation of the control mark.
 10. The memory resource of claim 8,wherein a portion of the control data is provided to a pre-printcomponent.
 11. The memory resource of claim 8, wherein a portion of thecontrol data is provided to a post-print component.
 12. A system,comprising: a printing apparatus to apply printing fluid on a substrateto generate an image portion on the substrate; a moveable imaging deviceto capture images of the substrate at a plurality of locations; and aprocessor to: select a plurality of features from image data of theimage portion to be utilized as a control mark for a print job to beperformed by the printing apparatus; generate control data for the printjob based on the selected control mark, wherein the control dataincludes a location of the control mark within the image portion;instruct the moveable imaging device to move to a location of theplurality of locations based on the location of the control mark;instruct the moveable imaging device to capture an image of the controlmark at the location; and determine a correction factor for a printingapparatus based on the captured image of the control mark.
 13. Thesystem of claim 12, comprising a folding apparatus and a cuttingapparatus.
 14. The system of claim 13, wherein the processor is to senda portion of the control data to the folding apparatus and the cuttingapparatus in response to the moveable imaging device capturing the imageof the control mark.
 15. The system of claim 12, wherein a size of theplurality of features are utilized to perform a scaling calibrationprocedure to determine the correction factor.